Pressure sensor and method for manufacturing the same

Abstract

A pressure sensor includes a housing with an interior enclosing a plunger unit and a measuring element. The plunger unit includes a distal plunger end separated along a longitudinal axis from a proximal plunger end and further away from the measuring element than the proximal plunger end and protruding from the housing. The proximal plunger end transmits a pressure of a medium prevailing outside the housing to the measuring element. A sleeve is fastened to the housing spaced apart from the distal plunger end by a gap. A sealing element seals the gap to prevent the medium from entering the housing interior.

What is claimed is: 
     
         1 . Pressure sensor for detecting the pressure of a medium, the pressure sensor elongating along a longitudinal axis and comprising:
 a housing that defines a housing interior;   a measuring element disposed in the housing interior;   a plunger unit disposed in the housing interior and including a proximal plunger end and a distal plunger end spaced apart along the longitudinal axis from the proximal plunger end, wherein the proximal plunger end has a disposition near the measuring element, wherein the proximal plunger end is configured to transmit from the measuring element a signal indicative of a pressure of a medium prevailing outside the housing and detected by the measuring element, wherein the distal plunger end protrudes from the housing and is disposed farther from the measuring element than the disposition of the proximal plunger end;   a sleeve fastened to the housing and spaced apart from the distal plunger end by a gap; and   a sealing element configured and disposed to apply a sealing pressure sufficient to seal the gap to prevent passage of the medium into the housing interior.   
     
     
         2 . Pressure sensor according to  claim 1 , wherein the sealing element is toroidal in shape and consists of elastically sealing material. 
     
     
         3 . Pressure sensor according to  claim 2 , wherein the sealing element defines a toroidal sealing body that defines a torus opening;
 wherein the distal plunger end protrudes through the torus opening.   
     
     
         4 . Pressure sensor according to  claim 1 , wherein the sleeve and the housing form a groove on a radially inner side of the sleeve with respect to the longitudinal axis; and wherein the sealing element is disposed in the groove. 
     
     
         5 . Pressure sensor according to  claim 4 , wherein the groove comprises a plurality of groove walls that exert a pre-compression on the sealing element disposed in the groove; and wherein the pressure in the gap acts on the sealing element as a compression in addition to the pre-compression, which pre-compression and which compression form the sealing pressure. 
     
     
         6 . Pressure sensor according to  claim 4 , wherein the housing-defines a distal housing end and a proximal housing end, which distal housing end is arranged along the longitudinal axis further away from the measuring element than the proximal housing end;
 wherein the sleeve defines a distal sleeve end and a proximal sleeve end, which distal sleeve end is arranged along the longitudinal axis further away from the measuring element than the proximal sleeve end; and   wherein the groove is arranged in the region of the distal housing end and the proximal sleeve end.   
     
     
         7 . Pressure sensor according to  claim 6 , wherein the groove-includes a groove wall defined in the proximal sleeve end and a groove wall defined in the distal housing end. 
     
     
         8 . Pressure sensor according to  claim 7 , the shape of the groove in a cross section cut along the longitudinal axis is rectangular or triangular or trapezoidal or round or semicircular. 
     
     
         9 . Pressure sensor according to  claim 1 , wherein the plunger unit includes a pre-load sleeve and a pre-load body; wherein the proximal plunger end merges into the pre-load sleeve; wherein the pre-load sleeve encloses a pre-load sleeve chamber, in which pre-load sleeve chamber the measuring element is arranged; wherein an end of the pre-load sleeve facing away from the proximal plunger end is fastened to the pre-load body; and wherein the measuring element is arranged on the longitudinal axis between the proximal plunger end and the pre-load body under a mechanical pre-load. 
     
     
         10 . Pressure sensor according to  claim 1 , wherein the housing is configured to be fastened in a bore of a wall of a pressure chamber in which the pressure of the medium is in the range from 50 bar to 5000 bar. 
     
     
         11 . Method for manufacturing a pressure sensor that includes a housing, a plunger unit and a sensing unit that includes a measuring element; which housing defines a housing interior and which plunger unit and which measuring element are arranged in the housing interior; which plunger unit defines a distal plunger end and a proximal plunger end, which distal plunger end is arranged on a longitudinal axis of the pressure sensor further away from the measuring element than the proximal plunger end and which distal plunger end protrudes from the housing and which proximal plunger end is in operative connection with the measuring element and configured to transmit to the measuring element, a signal indicative of a pressure of a medium prevailing outside the housing; the method comprising the following steps:
 moving the housing along the longitudinal axis over the plunger unit and then placing the housing on the sensor unit;   moving a sealing element along the longitudinal axis over the distal plunger end and then placing the sealing element on the housing; and   moving a sleeve along the longitudinal axis over the distal plunger end and then placing the sleeve on the sealing element and the housing so that the sleeve is spaced apart from the distal plunger end by a gap that is sealed sufficiently by the sealing element with a sealing pressure that prevents the medium from entering the housing interior.   
     
     
         12 . Method according to  claim 11 , wherein the distal plunger end includes a pre-load body and the housing is fastened to the pre-load body via a housing pre-load body connection; which housing pre-load body connection is arranged radially on the outside of the housing and on the pre-load body with respect to the longitudinal axis. 
     
     
         13 . Method according to  claim 11 , wherein a groove is formed radially on the inside of the sleeve and the housing with respect to the longitudinal axis by placing the sleeve on the housing around the sealing element. 
     
     
         14 . Method according to  claim 11 , further comprising the step of pre-stressing said sealing element between the sleeve and the housing. 
     
     
         15 . Method according to  claim 11 , wherein the sleeve placed on the housing is fastened to the housing via a sleeve-housing connection, which sleeve-housing connection is arranged radially on the outside of the sleeve and on the housing with respect to the longitudinal axis. 
     
     
         16 . The pressure sensor according to  claim 2 , wherein the elastically sealing material of the sealing element is a fluoroelastomer, a perfluoroelastomer, a rubber or an acrylonitrile-butadiene rubber.